1. Field of the Invention
The present invention relates to an apparatus and a method for positioning, handling and conveying structural parts in a conveying direction for surface finishing the structural parts hanging on frames, for example in an immersion bath for hot galvanizing, lacquering or powder coating.
2. Description of the Prior Art
In the surface finishing of various structural parts, such as rods or flat elements, the parts are conveyed loosely, on pallets or in carrying frames. The structural parts must then be hung, usually by hand, on suitable apparatus for the surface finishing treatment. For technical reasons, the hanging is usually effected overhead and/or in close quarters. Typical apparatus for hanging the structural parts are hook systems on conveyor chains, or hook or wire fastenings on crossheads or special frames. Automatic handling during surface finishing is usually too expensive and requires such high specialization that it can be amortized only in mass production operations. Sometimes, a number of different surface finishing treatments are needed, which requires additional grouping and re-hanging of the structural parts. After the surface finishing treatment, the finished parts must be manually removed, usually overhead, and be readied for delivery.
It is the primary object of this invention to provide a system which enables the structural parts to be charged to the system and removed therefrom with simple means, either manually or automatically, horizontally or vertically, while the structural parts are locked in position during treatment.
The above and other objects are accomplished according to one aspect of the invention with an apparatus which comprises successively arranged frames, each frame comprising two lateral blocks, two lateral braces, a transverse shaft connecting free ends of the lateral braces remote from the lateral blocks, and hooks for hanging the structural parts, the hooks being affixed to the transverse shaft and spaced from each other in a transverse direction, successive ones of the frames in the conveying direction being so close to each other that the structural parts hanging on the hooks are locked in position by the transverse shafts of the successive frames.
According to another aspect, the invention provides a method for positioning, handling and conveying structural parts for a surface finishing of the parts, which comprises conveying successively arranged frames in a conveying direction, hanging the structural parts on hooks carried by the frames, and maintaining successive ones of the frames in the conveying direction so close to each other that the structural parts hanging on the hooks are locked in position by the successive frames.
With such an apparatus or method, the structural parts may be inserted and removed during a horizontal or vertical conveyance, and the system may be sealed during transport and conveyance of the parts in a finishing bath while the parts are locked in position, to hold them securely, for example, in truck containers, during racking or galvanizing. During galvanizing, steel parts tend to float in the galvanizing bath and to become detached from the hooks on which they are hung, which the apparatus of the present invention prevents. Furthermore, the system provides ready accessability from above for wiping the bath liquid off during hot galvanizing, the structural parts may be readily singled for quality control or for lacquering, the apparatus may be manipulated with a crane or high-lift, and it may be deposited in a number of superposed planes in pallet shelves or in containers. For transport, charging and during surface finishing in an immersion bath, the structural parts may be tightly packed and securely locked in position. Long and heavy or sensitive hung structural parts will not freely swing. It is easy to single the structural parts automatically for lacquering or powder coating so that the parts are readily accessible from the side. The surface areas and masses of the apparatus directly involved in the surface finishing process are small and may, therefore, be readily protected. The hooking system may be readily produced and may be of noble materials, such as titanium or stainless steel, so that it is well adapted to automatic cleaning. The crossheads connecting the lateral blocks of the apparatus have a substantial distance from the finishing bath level, and they may be readily loaded and removed with a crane, a high-lift or other devices. They may be simply transported by conveyor chains, the crossheads of successive frames may be conveyed closely together in the conveying direction, and they may be rotated about their longitudinal axes and about a vertical axis. The system is flexible and, depending on the hooking system, it can handle structural parts of different lengths, widths and depths. It can handle profiled parts, tubes or solid parts.